Vignan University

About: Vignan University is a education organization based out in Guntur, Andhra Pradesh, India. It is known for research contribution in the topics: Control theory & CMOS. The organization has 1138 authors who have published 1381 publications receiving 7798 citations.

Compact symmetrical slot coupled linearly polarized two/four/eight element MIMO bowtie DRA for WLAN applications

Abstract: This paper presents a compact and low cost MIMO (Multiple-Input-Multiple-Output) Bowtie dielectric resonator antennas for two, four and eight elements for public safety entities (4.94–4.99 GHz) and indoor WLAN (5.15–5.35 GHz) applications. The fractional impedance bandwidth (4.72 GHz – 5.44 GHz) is 14.17% for all ports and strengthens the targeted frequency range gain. Two bubbled I-shape embedded inside the rectangular box defective ground structure to enhance the separation between ports by etching therefore over the operating frequency band, isolation between ports exceeds 25 dB and maximum ECC (envelope correlation coefficient) of 0.04. The designed compact unit cell antenna has a dimension of 30 × 25.6 mm2 (i.e. 0.5λ0 × 0.4 λ0 where λ0 is calculated at 5.2 GHz in the free space) and finally proposed 8-element antenna having a size of only 120 × 51.2 mm2 (2.07 λ0 × 0.88 λ0). Within their finest values, MIMO diversity performance parameters are obtained. The gain of the antenna unit cell, two, four and eight elements are 5.24 dBi, 5.49 dBi, 5.68 dBi and 6.2 dBi respectively and these gain values are most suitable for WLAN applications. To show the simulated performance, a prototype of all radiators would be manufactured and tested experimentally and measured results are good agreement with simulation result.

Suzuki‐Miyaura cross–coupling reaction in water: facile synthesis of (hetero) aryl uracil bases using potassiumorganotrifluoroborates under microwave irradiation.

Abstract: In this paper, we report the use of (hetero) aryl potassiumorganotrifluoroborate salts as versatile nucleophilic organoboron reagents in the Suzuki-Miyaura cross-coupling reaction of an electron rich 6-chloro 3-methyl uracil in water under microwave irradiation. A comparative study of the cross-coupling reaction of this chloro uracil analogue with different nucleophilic organoboron source revealed the superior reactivity of (hetero) aryl potassiumorganotrifluoroborates in water under microwave irradiation. Diversely functionalised (hetero) aryl uracil bases, which are known possess a wide range of applications in chemical biology, were efficiently synthesized using this optimised protocol.

Open MOFs with Unique Hexatopic Zinc-5,15-bis(4′-carboxyphenyl)-10,20-bis(3′,5′-dicarboxyphenyl)porphyrin Linker

Abstract: Characteristic coordination modes of tetrapodal and octapodal porphyrin linkers were combined in the design of a new hexapodal porphyrin linker. The custom-designed [(5,15-bis(4′-carboxyphenyl)-10,20-bis(3′,5′-dicarboxyphenyl)]porphyrin (H6HCPP) contains two trans-related 4-carboxyphenyl coordination sites similar to tetra(carboxyphenyl)porphyrin (H4TCPP) linker and two other 3,5-dicarboxyphenyl (isopthalate-type) functions related to octa(carboxyphenyl)porphyrin (H8OCPP) moiety. Synthesis of the H6HCPP was optimized for higher yields by utilizing excess concentration of TFA. The supramolecular reactions of zinc metalated linker Zn-H6HCPP with different metal centers afforded open hexacarboxy–metalloporphyrin frameworks (hcMPFs) perforated by wide intralattice voids. One 6-connected uninodal and two 6,6-connected binodal frameworks Mn-hcMPF (1), Co-hcMPF (2), and Zn-hcMPF (3) were obtained by employing transition metals Mn(II), Co(II), and Zn(II) as the exocyclic interporphyrin binding nodes. These framew...

Multi-Level Authentication Scheme for Improving Privacy and Security of Data in Decentralized Cloud Server

Abstract: In recent days cloud domain gains a lot of user attention in order to store and access the data from remote locations connected through the internet. As it is generally known that all the sensitive data come from remote locations will be stored in the centralized storage medium and then try to access the data from that centralized storage space controlled by the cloud server. It is facing a problem like there is no security for the data in terms of user authorization and data authentication from the centralized storage location. Hence, it is required to migrate for a new storage procedure like Decentralized storage of cloud data in which the systems that do not rely on a central authority, so that the collusion resistance can be avoided by maintaining a global identifier. Here, the term de-centralized access means granting multi authorities to control the access for providing more security for the sensitive data. The proposed research study attempts to develop a new scheme by adding a global identifier like Attribute Authority (AA) for providing access keys for the data users who wish to access the sensitive information from the cloud server. The proposed research work attempts to incorporate the composite order bilinear groups scheme for providing access facility for the data users and provide more security for the sensitive data. By conducting various experiments on the proposed model, the obtained result clearly tells that the proposed system is very efficient to access the data in a de-centralized manner by using a global identifier.